<?php
Class DB {

private $link_id;
private $handle;
private $is_log;
private $time;

//构造函数     
public function __construct() { 
$this->time = $this->microtime_float();
require_once("config.db.php");
$this->connect($db_config["hostname"], $db_config["username"], $db_config["password"], $db_config["database"], $db_config["pconnect"]);
$this->is_log = $db_config["log"];
if($this->is_log){
$handle = fopen($db_config["logfilepath"]."dblog.txt", "a+");
$this->handle = $handle;
}
}

//数据库连接     
public function connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect = 0,$charset='utf8') { 
if( $pconnect==0 ) {
$this->link_id = @mysql_connect($dbhost, $dbuser, $dbpw, true);
if(!$this->link_id){
$this->halt("数据库连接失败");
}
} else {
$this->link_id = @mysql_pconnect($dbhost, $dbuser, $dbpw);
if(!$this->link_id){
$this->halt("数据库持久连接失败");
}
}
if(!@mysql_select_db($dbname, $this->link_id)) {
$this->halt('数据库选择失败');
}
@mysql_query("set names ".$charset);
}

//查询      
public function query($sql) { 
$this->write_log("查询 ".$sql);
$query = mysql_query($sql, $this->link_id);
if(!$query) $this->halt('Query Error: ' . $sql);
return $query;
}

//获取一条记录（MYSQL_ASSOC，MYSQL_NUM，MYSQL_BOTH）                   
public function get_one($sql,$result_type = MYSQL_ASSOC) { 
$query = $this->query($sql);
$rt = & mysql_fetch_array($query, $result_type);
$this->write_log("获取一条记录 ".$sql);
return $rt;
}

//获取全部记录     
public function get_all($sql,$result_type = MYSQL_ASSOC) { 
$query = $this->query($sql);
$i = 0;
$rt = array();
while($row = & mysql_fetch_array($query, $result_type)) {
$rt[$i] = $row;
$i++;
}
$this->write_log("获取全部记录 ".$sql);
return $rt;
}

//插入     
public function insert($table,$dataArray) { 
$field = "";
$value = "";
if(!is_array($dataArray) || count($dataArray)<=0) {
$this->halt('没有要插入的数据');
return false;
}
while(list($key, $val) = each($dataArray)) {
$field .="$key,";
$value .="'$val',";
}
$field = substr( $field, 0, -1);
$value = substr( $value, 0, -1);
$sql = "insert into $table($field) values($value)";
$this->write_log("插入 ".$sql);
if(!$this->query($sql)) return false;
return true;
}

//更新     
public function update( $table,$dataArray,$condition="") { 
if(!is_array($dataArray) || count($dataArray)<=0) {
$this->halt('没有要更新的数据');
return false;
}
$value = "";
while( list($key, $val) = each($dataArray))
$value .= "$key = '$val',";
$value .= substr( $value, 0, -1);
$sql = "update $table set $value where 1=1 and $condition";
$this->write_log("更新 ".$sql);
if(!$this->query($sql)) return false;
return true;
}

//删除     
public function delete( $table,$condition="") { 
if( empty($condition) ) {
$this->halt('没有设置删除的条件');
return false;
}
$sql = "delete from $table where 1=1 and $condition";
$this->write_log("删除 ".$sql);
if(!$this->query($sql)) return false;
return true;
}

//返回结果集     
public function fetch_array($query, $result_type = MYSQL_ASSOC){ 
$this->write_log("返回结果集");
return mysql_fetch_array($query, $result_type);
}

//获取记录条数     
public function num_rows($results) { 
if(!is_bool($results)) {
$num = mysql_num_rows($results);
$this->write_log("获取的记录条数为".$num);
return $num;
} else {
return 0;
}
}

//释放结果集     
public function free_result() { 
$void = func_get_args();
foreach($void as $query) {
if(is_resource($query) && get_resource_type($query) === 'mysql result') {
return mysql_free_result($query);
}
}
$this->write_log("释放结果集");
}

//获取最后插入的id     
public function insert_id() { 
$id = mysql_insert_id($this->link_id);
$this->write_log("最后插入的id为".$id);
return $id;
}

//关闭数据库连接     
protected function close() { 
$this->write_log("已关闭数据库连接");
return mysql_close($this->link_id);
}

//错误提示     
private function halt($msg='') { 
$msg .= "\r\n".mysql_error();
$this->write_log($msg);
die($msg);
}

//析构函数     
public function __destruct() { 
$this->free_result();
$use_time = ($this->microtime_float())-($this->time);
$this->write_log("完成整个查询任务,所用时间为".$use_time);
if($this->is_log){
fclose($this->handle);
}
}

//写入日志文件     
public function write_log($msg=''){ 
if($this->is_log){
$text = date("Y-m-d H:i:s")." ".$msg."\r\n";
fwrite($this->handle, $text);
}
}

//获取毫秒数     
public function microtime_float() { 
list($usec, $sec) = explode(" ", microtime());
return ((float) $usec + (float) $sec);
}
}
